[RFC PATCH 10/17] selinux: Implement the watch_key security hook [ver #4]

From: David Howells
Date: Mon Mar 09 2020 - 08:18:54 EST


Implement the watch_key security hook to make sure that a key grants the
caller View permission in order to set a watch on a key.

For the moment, the watch_devices security hook is left unimplemented as
it's not obvious what the object should be since the queue is global and
didn't previously exist.

Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Acked-by: Stephen Smalley <sds@xxxxxxxxxxxxx>
---

security/selinux/hooks.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 4b6991e178d3..95be16d3f47a 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -6563,6 +6563,17 @@ static int selinux_key_getsecurity(struct key *key, char **_buffer)
*_buffer = context;
return rc;
}
+
+#ifdef CONFIG_KEY_NOTIFICATIONS
+static int selinux_watch_key(struct key *key)
+{
+ struct key_security_struct *ksec = key->security;
+ u32 sid = current_sid();
+
+ return avc_has_perm(&selinux_state,
+ sid, ksec->sid, SECCLASS_KEY, KEY_NEED_VIEW, NULL);
+}
+#endif
#endif

#ifdef CONFIG_SECURITY_INFINIBAND
@@ -7078,6 +7089,9 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(key_free, selinux_key_free),
LSM_HOOK_INIT(key_permission, selinux_key_permission),
LSM_HOOK_INIT(key_getsecurity, selinux_key_getsecurity),
+#ifdef CONFIG_KEY_NOTIFICATIONS
+ LSM_HOOK_INIT(watch_key, selinux_watch_key),
+#endif
#endif

#ifdef CONFIG_AUDIT